\begin{tikzpicture}
    \tkzDefPoints{0/0/B, 3.5/0/C, 0.8/2.5/A, 1.5/1/P}
    \tkzDefPointOnLine[pos=1.3](A,P)  \tkzGetPoint{D}

    \tkzDrawPolygon(A,B,C)
    \tkzDrawSegments(B,P  C,P)
    \tkzDrawSegments[dashed](A,D)
    \tkzLabelPoints[above](A,P)
    \tkzLabelPoints[below](B,C,D)
\end{tikzpicture}

